Jewelry Precious

Dushan Jade (Du Jade) - also Called Nanyang Jade

Dushan Jade is a kind of nephrite and one of the most important jades in China. 

Hardness: 6.0-6.5
Specific gravity: 2.73-3.18 g/cm3
Color: A piece of Dushan Jade may have more than two or three colors, common colors are white, green, purple, yellow, red, black, etc.
Transparency: transparent to translucent
Luster: glass or oil sheen
Under the microscope: black spots, not bright colors, a variety of mineral inclusions.

Dushan Jade was produced in the Dushan, Nanyang in Henan Province, also known as "Nanyang jade" or "Henan Yu," also referred to as Du Yu (Du Jade)
As early as 6000 B.C. Dushan Jade has been mined.  In the Yin Ruins of Shang Dynasty (1,600 B.C. to 1,050 B.C.) in Anyang, Dushan Jade ornaments was unearthed in the tomb of the Shang kings.
Because of its bright color, good transparency and other advantages, Dushan Jade is one of China's "four big-name" list. High-end Dushan Jades are emerald green, and similar Burmese jadeite, so has a reputation of "Nanyang Jadeite." Common Dushan Jade are used for a variety of furnishings and bracelets, rings, necklaces and other ornaments.
Dushan Jade is multi-color, and can be divided into eight varieties according to the colors.
Green Dushan Jade: Green to emerald green, translucent, delicate texture, similar to jadeite, a luster of shiny glass.
Red Dushan Jade: also known as "Furong Jade." Light red to red, delicate texture, luster is good.
White Dushan Jade: Secheng white or off-white, delicate texture, with grease-like luster. The species include cream white jade, white jade, such as flooding.
Purple Dushan Jade: dark purple, poor transparency.
Yellow Dushan Jade: yellow-green.
Black Dushan Jade: black like ink, is also known as "Mo Yu."
Blue Dushan Jade: blue, poor transparency.
Variegated Dushan Jade: a variety of mixed colors.
Good Dushan Jade should have good transparency, delicate texture, and no cracks. Green Dushan Jade, Red Dushan Jade, and White Dushan Jade have higher value. In addition, the use of jade pieces in different colors to imitate the natural production of colors is also good.

According to geological workers in Henan, Dushan Jade is a kind of altered plagioclase rock, with mica and other minerals. Under microscope, Dushan Jade contains a variety of altered minerals. Its Chemical analysis result is: silica 41 to 45 percent, alumina 30.71 to 34.14 percent, magnesia 0.28 to 1.73 percent, potassium oxide 0.02 to 2.64 percent, Ferric Oxide from 0 to 0.8 percent, ferrous oxide 0.27 to 0.88 %, Manganese oxide 0.02 to 0.1 percent, chromium oxide 0.01 to 0.34 percent, crystal water 0.23 to 0.74 percent, carbon dioxide 0.06 to 0.52 percent. The trace element analysis results are: 0.01 to 0.5 percent chromium, nickel less than 0.1%, 0.1% to 0.001 vanadium, manganese 0.01 to 0.05 percent, titanium 0.001 to 0.5 percent.